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Now that we are in deep winter, I have seen this happen on cold days(-9C and below).

Even if the engine temperature gauge shows normal(middle of the scale), the heater(from the dash vents) blows cool/cold air when the engine is at idle. Once you get moving, or if in park and you rev the engine, then you start to get warm air.

I even had the temperature set to the max which is 32C for us Canadians.

Anyone seeing the same thing?

I took it to the dealer and of course it wasn't that cold that day, and they didn't see anything.

It's going to be cold again this weekend here in the Toronto area, so I am going to try again.

I have a 2009 Flex and have the same problems. I love the car but for two things: the suspension sucks and the cabin heat is unacceptable.

The ford dealership has replaced the thermostat, temp sending unit, heater core, and the cabin temp sensor, and there is little improvement. It also males no difference whether the rear heat is on or off. They are as frustrated as I. With higher engine RPM's the air temp goes as high as 150F, but at idle, the air temp drops to about 100 degrees. In Minnesota in January, this is unacceptable!!

I believe the problem maybe the water pump. At idle there seems to be not enough fluid moving through the heater core to keep it hot, but once you rev the engine, it heats up just fine. And with the new heater core we are sure the heater core is not plugged. With the traction control system, I am always trying to find dry pavement to excellerate on to get some heat in the cabin.. not safe..

This week I am going to insist that they put a higher flow water pump in. Let me know anyone's thoughts.

As I mentioned, we did drive around this weekend and it was cold here in Toronto.

For some reason, the cabin temperature "seemed" warmer than the previous cold snap.

I asked the dealer if they did anything the last time, and all they did was connect it to the computer and download the lasest s/w and check all settings.

Today is another cold day and I'm going to try this again. I even have to go back to the dealer to get a plastic part the broke on the driver seats where the lower seat belt is attached. A small 2"x2" chunk, that has some terrible tiny plastic clips holding it on.

Would like to hear from others on their cabin temperature experiences. Please post, good or bad.

Well, tonight it was -8C outside and it is pumping out heat like no tomorrow. I tried changing to different temperature settings, blowing air at feet, dash and turning off and on the rear heater as well.

Each time, no problem with getting heat.

I can only deduce that the computer work the dealer did, resolved my problem.

To make this fully qualified, I'll have to wait till we get into the minus teens Celsius, which is when I first noticed it.

-6 today and my Flex is still pouring out cold air with the engine warm.. However yesterday it was up around +12 and the cabin heat worked perfect. My service manager spoke with Ford and they are aware of the cold cabin air temp and are working on a fix. Ford said that they have seen most of the problems when the outside air temp drops below 0F. My exact situation. He said that there are hundreds, of Flexes having the same problems. They also know that the thermostat, sensor, and heater core have not solved the problem. He said it could be several weeks before they see a fix. I will keep you all posted.

this past Saturday it was -20C here in Toronto and I had no problem with cabin temperature. We were up north of Toronto skiing.

I just talked to my service manager to find out what they did back a couple of weeks ago when I took it in. BTW, he is not aware of a statement from Ford Corporate that there is a problem.

Anyway, in his words they recalibrated to factory settings the PCM and "Head Unit". No exactly sure what this is. He explained that it controls the electronics/computers in the vehicle. Since this change I have had no issues with cold air.

I have noticed the similar problems with the Climate Control. It just doesn't seem to work well. Last night it was around 38F degrees and I had the climate control turned on to 75F degrees with no other options (like defrost), and it was pumping out cold air and the fan was blowing hard. It was only a 15 minute car ride but it should have been toasty by the time I arrived and it wasn't.

At Seattle temperatures, this isn't a big deal (especially with seat heaters), but I do expect this to work.

I don't want to just voice complaints because I really love so many aspects of this car (especially the ride)!

I'm sure Ford will figure this out soon. But if anyone knows of a fix please post it here!

Hey all!! I've seen a lot of posting on the forum about this issue. If you go to Ford Forums you'll also see the stuff I'm about to mention. I have also had this issue, as have a NUMBER of the new Ford Flex's. It is not related to particular model, etc....I have a Limited. Basically, the heater pumps cold air when idling...in the Front only. And thank God for that becuase I was worried about my poor babies in the back seat. I digress. In any case. FORD IS AWARE OF THE PROBLEM. Our dealerships around this area...multiple of them who have heard from us buyers...have tried the whole gammut of things to fix it. Cardboard in the grill, plugged hoses, replaced Thermostats, Heater Cores, etc. THESE DO NOT FIX THE ISSUE. So, don't waste your time like we all did by trying those things. Basically, what we've been told is to hang tight, Ford's investigating and experimenting with some things. I heard that back in January as well and I'm still waiting. Of course by the time they think they have something, we'll all have to wait another year for the cold Dec/Jan/Feb temps to actually TEST what they come up with, eh? Good luck to you all, put some long johns under the jeans and little foot warmers in those boots for the time being :-) I LOVE MY FLEX...this is just an unfortunate deal I guess. I'll be terribly disappointed when they actually tell us its a design flaw. Funkmaster Flex lives in Miami...they don't worry about freezing down there. !!

Now that it's a month later and surely the Minnesota temps we've had, have you had any more issues with your heater after the 'recalibration'??

Interesting post that Ford is aware of the problem.

this past Saturday it was -20C here in Toronto and I had no problem with cabin temperature. We were up north of Toronto skiing.

I just talked to my service manager to find out what they did back a couple of weeks ago when I took it in. BTW, he is not aware of a statement from Ford Corporate that there is a problem.

Anyway, in his words they recalibrated to factory settings the PCM and "Head Unit". No exactly sure what this is. He explained that it controls the electronics/computers in the vehicle. Since this change I have had no issues with cold air.

I have noticed the similar problems with the Climate Control. It just doesn't seem to work well. Last night it was around 38F degrees and I had the climate control turned on to 75F degrees with no other options (like defrost), and it was pumping out cold air and the fan was blowing hard. It was only a 15 minute car ride but it should have been toasty by the time I arrived and it wasn't.

At Seattle temperatures, this isn't a big deal (especially with seat heaters), but I do expect this to work.

I don't want to just voice complaints because I really love so many aspects of this car (especially the ride)!

I'm sure Ford will figure this out soon. But if anyone knows of a fix please post it here!

Well my car is in the shop and I think the heat problem is fixed. I can't speak for the rest of you but it turns out that my heat problem was due to a loose clamp that was causing engine coolant to leak. According to the service technician this was causing the lack of heat problem. 2 days ago the clamp finally gave way and my temperature engine light turned on at an intersection. I had to drive for another 5 minutes to find a safe place to pull over. Then I called Ford Roadside Assistance and the car was towed to the dealer.

I sure hope that I didn't harm my engine, and hopefully my heat problem is solved.

Well my car is in the shop and I think the heat problem is fixed. I can't speak for the rest of you but it turns out that my heat problem was due to a loose clamp that was causing engine coolant to leak. According to the service technician this was causing the lack of heat problem. 2 days ago the clamp finally gave way and my temperature engine light turned on at an intersection. I had to drive for another 5 minutes to find a safe place to pull over. Then I called Ford Roadside Assistance and the car was towed to the dealer.

I sure hope that I didn't harm my engine, and hopefully my heat problem is solved.

You know, something similar (clamp related) to that happened to my mom while test driving the Flex.

When driving it, she decided to floor it to see what it'd do. Well, she had accidentally put it into "L" instead of "D," but I don't really know if that affected it. Anyways, after a while driving, the air started getting hot (it was cold), and the car I believe was overheating and eventually went into fail safe mode....we had to pull over. My family and I were by ourselves (no dealer person - we've known our salesman for years, so he lets us take cars w/out anybody), so he eventually showed up. After we all looked in the engine compartment, we discovered a clamp IIRC going to the radiator or something had come completely off, causing the problem. We weren't far from the dealer but closer to our house, so eventually after it cooled down, my dad put some water in (IIRC) and drove it back to the dealer where they could fix it.

In a way, I was glad it happened to us (we basically already knew we were gonna order one at that point) rather than another customer.....it definitely wouldn't have left them with a good impression.

I live in Northern Alberta Canada and all was good with my flex through the winter which I bought last June. I was worried that the automatic setting would blow air through the center dash vents as you cannot close them manually but I was happy to see that when the outside temperature got colder the center vents would not blow in the automatic setting.

When i'm idiling here in florida and now it's been like 96, 98 degrees, i stop at a light for the nearly five
minutes these lights last here and bam ........the cold air stops flowing and the car get hot again.

in traffic this really sucks here, add our humidity and high temps and this car a/c is terrible.

if i'm zooming down the interstate at 70 or so.......... the a/c gets to optimum temp but then cycles like crazy
so it never has a chance to satisfy the cabin to make the creatures who drive these Ford better idiea bullshit cars. I"m just off a 5 day shop visit with the flex and it's no better the second time in there.

I'm going for three...........You know 3 strikes and your out......!! I'll play hard ball. I"m tired of driving these new lemons for these dumb shit engineers with the dam light bulb going off in their heads to save the company money and screw us customers that buy american so to speak.

Well sorry to blow off steam here but isn't it funny that the two things may be related, computer controlled and not working right..... They did tell me about the service bulletin for the computer fix but it think it's worse now then before i first took it in .

Good luck to you all with the problems. Look up all my post for my troubles since last october/2008

Hello, I am trying to find additional information on this topic. It appears the thread ends in October 2009 with a link to alldata from Gotchagain but I tried the link and it returns an error. I just purchased a new 2009 Flex with an early mfg dat of 8/2008 so it was sitting around at the dealer for a while. Well I have the exact same issues with the fron heat blowing very cold on the floor when at idle. The rear heat blows hot all the time so the the passengers are fine. I have noticed this issue with temps as high as 10F - 15F and it gets worse as the temps drop. I am planning to bring it back to the dealer and would like to know what I can expect and if I should print out this thread to try and save some time.

By the way my family absolutely loves the car and it is the perfect car for a family with 3 growing kids.

ISSUE:
Some 2009 Flex vehicles built before 1/19/2009 may exhibit a customer concern of reduced heater duct discharge temperature when the vehicle engine is brought down to an idle speed.

ACTION:
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

Heater Performance Verification Test

Drive vehicle minimum 20 minutes.
Ensure that the thermostat is open by checking for heat at the upper radiator hose. If the thermostat is not open continue to drive.
Set the front climate temperature control to 90 °F (32 °C) and turn off the auxiliary climate control.
Set the mode to panel/vent and A/C switched off. Do not set to recirculation mode.
Set the blower to highest speed, open all panel vents.
Idle the engine for additional 20 minutes at an ambient of 60 °F (15.5°C) or above with the hood down.
The left center vent discharge air temperature should be a minimum of 137 °F (58 °C) at 60 °F (32 °C) ambient.
If the heater performance meets the minimum 137 °F (58 °C) criteria, stop with this procedure and proceed to the Workshop Manual (WSM), Section: 412-Climate Control System Diagnostics and Testing.
If the heater performance does not meet the minimum 137 °F (58 °C) criteria, then proceed to Cooling System Flush.
Flushing Equipment Fabrication

Prior to starting the service flush procedure prepare the fresh water supply hose and the drain hose. Obtain two (2) hose coupling adapters, six (6) number 12 hose clamps and one (1) garden hose (obtain locally). The garden hose can be either a 5/8" (16 mm) or 3/4" (19 mm). The couplings can be 5/8" (16 mm) x 3/4" (19 mm) or 3/4" (19 mm) x 3/4" (19 mm) depending on the size garden hose used. The vehicle hose and thermostat port are 3/4" (19 mm) in size. (Figure 1)

Figure 1 - Article 09-10-1

Using a coupling adapter and hose clamps, Cut the garden hose to length (One end of the hose must reach from the vehicle to a fresh water supply faucet and the drain hose end should be long enough to drain the engine away from the vehicle) and attach a 2' (61 cm) length of heater hose to the garden hose to be used as the fresh water supply. The heater hose will prevent kinking at the tight area of the engine compartment. (Figure 2)

Figure 2 - Article 09-10-1

Using a coupling adapter and hose clamps, attach a 2' (61 cm) length of heater hose to the remaining section of garden hose to be used as the drain hose. The heater hose will prevent kinking at the tight area of the engine compartment. (Figure 3)

Figure 3 - Article 09-10-1

Cooling System Flush

NOTE: DISPOSE OF OLD COOLANT AND FLUSHING WATER CONTAMINATED WITH ANTIFREEZE AND CLEANING CHEMICALS IN ACCORDANCE WITH LOCAL, STATE OR FEDERAL LAWS.

Drain the cooling system. Refer to WSM Section 303-03. Leave the draincock open and splash shield off.
Remove the air cleaner assembly. Refer to WSM Section 303-12
Disconnect the heater core outlet hose (Item 4) and the heater core inlet hose (Item 5) from the thermostat housing and position them aside. (Figure 4)

Install a pinch off plier (Rotunda tool SKT7603 or equivalent to the rear heater core inlet hose (Item 5, Figure 4) just below the inlet tee fitting. Do not remove pinch off pliers until after the rear heater core has been flushed.
Connect the fresh water supply hose to the heater outlet hose (Item 4, Figure 4).
Attach a drain hose to the heater inlet hose (Item 5, Figure 4) to prevent coolant from splashing and staining the engine compartment.
Back flush the front heater core through the heater outlet with tap water until water is clear approximately 4 gallons (15 L).
Disconnect the rear heater core inlet hose at the rear of the vehicle. (Figure 5)

Figure 5 - Article 09-10-1

Install pinch off pliers to the drain hose (Item 5 Figure 4).
Position drain pan underneath rear heater core.
Turn on the water supply and back flush front and rear heater cores with tap water until approximately 2 gallons (7.6 L) have filled the drain pan.
Remove pinch off pliers from rear heater core inlet hose (Item 5, Figure 4) and install on the rear heater core outlet hose (Item 4, Figure 4) just below the outlet tee fitting.
Back flush the underbody metal heater inlet line with tap water until water is clear.
Connect the rear heater core inlet hose.
Remove pinch off pliers from drain hose and pinch off rear heater core inlet hose (Item 5, Figure 4). Leave heater core outlet hose (Item 4, Figure 4) pinched off.
Disconnect the drain hose and reconnect heater core inlet hose to thermostat housing.
Connect the garden drain hose to the heater core outlet hose (Item 4, Figure 4). This will be used to allow the engine to drain away from the engine compartment.
Connect the fresh water supply hose to the heater return port (Item 10, Figure 4) on the thermostat housing. (Figure 4)
Install the air cleaner assembly. It is not necessary to install the bolts; air cleaner will be removed again. It is important to install the air cleaner assembly to prevent stalling the engine. Make sure that the two air cleaner feet are seated into the rubber grommets under the air cleaner assembly. The air cleaner outlet pipe should be securely sealed to prevent unmetered air from entering the engine.
CAUTION: THE UPPER RADIATOR HOSE MUST BE PROPERLY POSITIONED BELOW THE LOCATING BRACKET ON THE COOLING FAN SHROUD AS SHOWN. FAILURE TO PROPERLY POSITION THE HOSE COULD RESULT IN ENGINE OVERHEATING. (FIGURE 7)

Figure 6 - Article 09-10-1

Install and configure the Integrated Diagnostic System (IDS) scan tool to monitor and activate the engine RPM number and High Speed Cooling Fan FAN_CTRL.
Enter the vehicle information and then select the datalogger tab and the check tick icon from the toolbox menu.
Select powertrain from data logger menu then select engine, check tick icon.
Select the eraser Icon and then the check tick icon to clear all selections.
Select to highlight both the FAN_CTRL number and the RPM number buttons.
Select the check tick icon to display the FAN_CTRL number and the RPM number pids.
Turn on the fresh water supply. Allow the degas bottle to fill to the max cold fill range then tighten the cap to prevent overflowing (radiator drain valve should still be open).
Start the engine.
Using active command on the IDS, set the engine RPM to 2000 RPM.
Highlight the RPM display, and then select the number icon.
Select the button icon below the number icon to activate control of RPM.
Press the plus icon below the button icon to increase the RPM speed.
NOTE: It is important to exit IDS active command by using the eraser button on the IDS to prevent engine stalling.

Run the engine for (2) minutes (radiator drain valve should still be open, pressure cap installed, and coolant draining from the heater core outlet drain hose). It may be necessary to adjust the fresh water supply flow rate and crack the degas bottle cap periodically to ensure the system remains full of fluid throughout the procedure.
Return the engine to normal idle by selecting the eraser button on the IDS.
Stop the engine and turn off the fresh water supply.
Slowly remove the degas bottle cap.
Allow system to drain through the radiator drain valve.
Remove the air cleaner assembly.
Remove pinch off pliers from both rear heater core hoses.
Disconnect flush hoses from the heater return port and heater core outlet hose (Item 4, Figure 4).
Reconnect the heater core outlet hose (Item 4, Figure 4) to the thermostat return port.
Install air cleaner assembly. It is not necessary to install the bolts, air cleaner will be removed again.
Once the radiator is completely drained, close the radiator drain valve. The Heating Ventilation Air Conditioning (HVAC) blower motor must be turned off to make sure the thermostat opens. The high speed fan active command must be off to make sure the thermostat opens.
Add one (1) 22 fluid oz. bottle of Motorcraft® Premium Cooling System Flush to the degas bottle. (Do not use Ford Neutral pH Iron Cleaner, F8AZ-19A503-AA, or Motorcraft Engine Cooling System Iron Cleaner as these products are for rust removal).
Add fresh water to the degas bottle until the water reaches the maximum cold fill range. Follow WSM, Section 303-03 filling procedures.
Start the engine and let idle with the degas cap off for (2) minutes to allow trapped air in the engine to escape.
Stop the engine and wait for (1) minute to make sure air is purged from the radiator.
Add additional water to the bottle if required to bring the volume up to the maximum cold fill level.
Bleed air from the cooling system using the following procedure.
Close the degas bottle cap.
Start the engine and let idle until the engine reaches normal operating temperature and the thermostat is fully open. A fully open thermostat can be verified by the radiator fan cycling on at least once.
Turn the engine off for 1 minute.
Run the engine at a minimum of 3500 RPM for 30 seconds.
Run the engine at idle for 30 seconds.
Repeat steps 3-5 a total of 10 times.
CAUTION: THE FLUSHING SOLUTION CONTAINS NO GLYCOL, THE SYSTEM WILL BOIL BEFORE THE FANS TURN ON IF THE PRESSURE CAP IS NOT FITTED CORRECTLY.

Remove the air cleaner assembly.
Install pinch off pliers on rear heater inlet (Item 5, Figure 4) and rear heater outlet hoses. (Item 4, Figure 4)
Install air cleaner assembly. It is not necessary to install the bolts, air cleaner will be removed again.
Start engine
Using active command with IDS set the engine RPM to 2000 RPM.
Run the engine for (5) minutes at 2000 RPM to and allow the thermostat to open.
WARNING: IF THE ENGINE OVERHEATS OR THE FLUID LEVEL DROPS BELOW THE MINIMUM FILL LINE, SHUTOFF THE ENGINE AND ADD FLUID TO THE DEGAS BOTTLE MAXIMUM FILL LINE ONCE THE ENGINE COOLS. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN DAMAGE TO THE ENGINE. WARNING ALWAYS ALLOW THE ENGINE TO COOL BEFORE OPENING THE COOLING SYSTEM. DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHEN THE ENGINE IS OPERATING OR THE COOLING SYSTEM IS HOT. THE COOLING SYSTEM IS UNDER PRESSURE; STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY.

Return the engine to normal idle by using the eraser button on the IDS.
Stop the engine.
Remove the air cleaner assembly.
Remove pinch off pliers from both rear heater core hoses.
Install air cleaner assembly. It is not necessary to install the bolts, air cleaner will be removed again.
Key on engine off.
Using active command with IDS turn on the high speed cooling fan.
With the ignition key on and the engine off highlight the FAN_CTRL number display.
Enter IDS active command by selecting the number icon.
Select the button icon below the number icon to activate control of the cooling fan.
Press the plus icon below the button icon to turn on the cooling fan.
Wait 5 minutes with high speed fan running before continuing to next step.
Turn off the high speed fan by selecting the eraser button on the IDS. Turn off the ignition key.
Slowly remove the degas bottle cap and top off the degas bottle with tap water.
Start the engine and let Idle with the degas cap off for two (2) minutes to allow trapped air in the engine to escape.
Stop the engine and wait for (1) minute to make sure air is purged from the radiator.
Add additional water to the bottle if required to bring the volume up to the maximum cold fill level.
Install the degas bottle pressure cap.
Start engine.
Using active command with IDS set the engine RPM to 2000 RPM.
Run the engine for ten (10) minutes at 2000 RPM to and allow the thermostat to open.
WARNING: IF THE ENGINE OVERHEATS OR THE FLUID LEVEL DROPS BELOW THE MINIMUM FILL LINE, SHUTOFF THE ENGINE AND ADD FLUID TO THE DEGAS BOTTLE MAXIMUM FILL LINE ONCE THE ENGINE COOLS. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN DAMAGE TO THE ENGINE. ALWAYS ALLOW THE ENGINE TO COOL BEFORE OPENING THE COOLING SYSTEM. DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHEN THE ENGINE IS OPERATING OR THE COOLING SYSTEM IS HOT. THE COOLING SYSTEM IS UNDER PRESSURE; STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY.

Return the engine to normal idle by using the eraser button on the IDS.
Stop the engine.
Key on engine off.
Using active command with IDS, turn on the high speed cooling fan.
With the ignition Key on and the engine off highlight the FAN_CTRL number display.
Enter IDS active command by selecting the number icon.
Select the button icon below the number icon to activate control of the cooling fan.
Press the plus icon below the button icon to turn on the cooling fan.
Wait five (5) minutes with high speed fan running before continuing to next step.
Turn off the high speed fan by selecting the eraser button on the IDS. Turn off the ignition key.
Slowly remove the degas bottle cap and rinse with fresh water to clean the Motorcraft® Premium Cooling System Flush off of the cap.
Open the radiator drain valve and allow the system to completely drain.
Remove the air cleaner assembly to gain access to thermostat housing and disconnect the heater core outlet hose (Item 4, Figure 4).
Attach the drain hose to the heater core outlet hose (Item 4, Figure 4) and the fresh water supply hose to the heater return port on the thermostat housing.
Install air cleaner assembly. It is not necessary to install the bolts, air cleaner will be removed again.
Turn on the fresh water supply. Allow the degas bottle to fill to the maximum cold fill range then install the degas bottle cap. Tighten the cap to prevent overflowing (radiator drain valve should still be open).
Start the engine and let idle for two (2) minutes to allow trapped air in the engine to escape.
Stop the engine and wait for one (1) minute to make sure air is purged from the radiator.
Add additional water to the bottle if required to bring the volume up to the maximum cold fill level.
Install the degas bottle pressure cap.
Using active command with IDS set the engine RPM to 2000 RPM.
Run the engine for five (5) minutes at 2000 RPM. (radiator drain valve should still be open, pressure cap installed, and coolant draining from the heater core outlet drain hose). It may be necessary to adjust the fresh water supply flow rate and crack the degas bottle cap periodically to ensure the system remains full of fluid throughout the procedure.
Stop the engine and turn off the fresh water supply.
Slowly remove the degas bottle cap.
Allow system to drain through the radiator drain valve.
Remove the air cleaner assembly.
Disconnect flush hoses from the heater return port and heater core outlet hose (Item 4, Figure 4).
Connect the heater core outlet hose (Item 4, Figure 4) to the thermostat return port.
Install the air cleaner assembly. Refer to WSM Section 303-12.
Run fresh water through the degas bottle to remove residual Motorcraft® Premium Cooling System Flush.
Once the radiator is completely drained, close the radiator drain valve and install the splash shield. The engine at this stage is filled with pure water. The engine holds approximately 50% of the cooling system capacity.
Add 5.8 qts. (5.5 L) for base models and 6.3 qts. (6.0L) for trailer tow models (has oil cooler) of 100% pure concentrate coolant, Motorcraft® Premium Gold Engine Coolant with Bittering Agent, to the cooling system.
Top off the degas bottle to 1" (25 mm) above the top of the cold fill range with fresh water.
Bleed air from the cooling system using the following procedure.
Close the degas bottle cap.
Turn the HVAC system to off.
Start the engine and let idle until the engine reaches normal operating temperature and the thermostat is fully open. A fully open thermostat can be verified by the radiator fan cycling on at least once.
Turn the engine off for one (1) minute.
Run the engine at a minimum of 3500 RPM for 30 seconds.
Run the engine at idle for 30 seconds. If the engine overheats or the fluid level drops below the top of the cold fill range, shut off the engine and add fluid to 1" (25 mm) above the top of the cold fill range once the engine cools.
Repeat steps 4-6 a total of 10 times.
WARNING: ALWAYS ALLOW THE ENGINE TO COOL BEFORE OPENING THE COOLING SYSTEM. DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHEN THE ENGINE IS OPERATING OR THE COOLING SYSTEM IS HOT. THE COOLING SYSTEM IS UNDER PRESSURE; STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY.

Check the engine coolant level in the degas bottle and fill to 1" (25 mm) above the top of the cold fill range when warm or to the top of the cold fill range line when cold.
Install the degas bottle cap to at least one audible click.
Perform Heater Performance Verification Test.
If heater performance is restored to the minimum 137 °F (58 °C) criteria return the vehicle to the customer.
If heater performance is not restored to the minimum 137 °F (58 °C) after the cooling system flush, replace the front heater core. Refer to WSM, Section 412-01 for removal and installation.

ISSUE:Some 2009 Flex vehicles built before 1/19/2009 may exhibit a customer concern of reduced heater duct discharge temperature when the vehicle engine is brought down to an idle speed.

There is a new TSB out regarding this issue which replaces the old one listed here (Forget the new TSB#). Ford is aware of it so tell your service guys to give there heads a shake and actually look it up.

We are currently dealing with Jubilee ford in Saskatoon, and in contact with Ford Canada who informed us the engineers are aware and working on a fix. It Hits -40 Celsius + at times in Saskatchewan, and we have a little girl as well. We recently picked up an 09 Flex to discover the same problem NO HEAT AT IDLE. So far we have used 2 loaners from the dealer, both Flex's and both with the same problem..

We won't be letting this go until it is resolved to our satisfaction. Jubilee in all fairness has so far been awesome to deal with and want a fix as much as I do. Unfortunately it is up to the engineers at Ford to supply a fix. Who knows when, but it might be a good time for them to get it together and fix it, with all the recalls currently going on (ie-Toyota) I think about 9 million vehicles currently recalled, though Ford holds the record for recalls at about 14 million some years back...

The more people we can get to complain to Ford about this defect in the design the better!

The only time we notice this on our flex is in the morning when we start it up and let it idle in the driveway to warm up and defrost the insides, it does not warm up as you would expect after 10 or 15 minutes. The important point everyone has to be aware of this problem only happens when idling. if you driving down the road the heat works fine as long as you keep driving, if you stop and idling again for a period of time it will start blowing cold.

So people saying their heat works fine when they drive around it will work fine.

To me this appears to be a software or control system problem. it feel like the damper control is open to the fresh air position and is not mixing in any or enough warm air from the heater. When you turn on the front window defrosters full blast it seems to work well, it heats up and melts snow and ice off the window, but as soon as you return to normal operation it starts blowing cold again.

Update 3/6/2010 from Montana - The dealer performed the new TSB mentioned which appears to be a heavy duty flush of the cooling system to remove "stuff" (quote from service manager) from the front heater core and system.

I was waiting to write this update until I was able to confirm the fix. Well we went north to Mall of America a couple of weeks ago and the heater was a champ blowing lots of hot air while the temp outside was -10F. I stayed parked in the car for 30 minutes while waiting for a Pizza and the heater continued to blow hot the entire time. In the morning the car also heated up normally and delivered reliable heat.

The dealership called to check on the fix and I explained everything was in working order. The service manager commented how involved the TSB was and time consuming. It was their first such repair and I want to thank the folks on this forum for their help. I am not sure the dealer would have located the TSB without your help. I hope others have the same success and no one has to have their new dash removed to install a new heater core.